1. Field of the Invention
The present invention relates to a substrate processing apparatus for processing a substrate, and to a substrate transport method to be implemented by the substrate processing apparatus. Examples of the substrate to be processed and transported include semiconductor wafers, substrates for liquid crystal display devices, substrates for plasma display devices, substrates for FED (Field Emission Display) devices, substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photo masks, and substrates for solar cells.
2. Description of Related Art
In production processes for semiconductor devices and liquid crystal display devices, substrates such as semiconductor wafers and glass substrates for the liquid crystal display devices are treated with treatment liquids. A substrate processing apparatus of a single substrate processing type adapted to process a single substrate at a time is disclosed, for example, in U.S. Patent Application Publication No. 2009/0252578 A1.
The substrate processing apparatus includes a carrier retaining unit which retains a plurality of carriers, substrate processing units which each process a substrate, two inversion units vertically stacked between the carrier retaining unit and the substrate processing units, an indexer robot which transports a substrate between the inversion units and the carrier retaining unit, and a main transport robot which transports a substrate between the inversion units and the substrate processing units. The inversion units are each capable of horizontally holding a substrate and rotating the substrate 180 degrees about a horizontal axis (rotation axis) to invert the substrate. The indexer robot and the main transport robot can access the respective inversion units.
The inversion units each include a plurality of substrate holders which each horizontally hold a substrate. Where the number of substrates to be simultaneously transported by the indexer robot differs from the number of substrates to be simultaneously transported by the main transport robot, the number of the substrate holders to be provided in each of the inversion units is twice a greater one of these substrate numbers. Where the number of the substrates to be simultaneously transported by the indexer robot is equal to the number of the substrates to be simultaneously transported by the main transport robot, the number of the substrate holders to be provided in each of the inversion units is twice the number of the substrates to be simultaneously transported by each of the transport robots (the indexer robot and the main transport robot). Where the transport robots are each adapted to transport a single substrate at a time, for example, two substrate holders are provided in each of the inversion units. Further, the substrate holders provided in each of the inversion units are disposed symmetrically on opposite sides of the rotation axis. Where two substrate holders are provided, for example, the two substrate holders are disposed symmetrically on upper and lower sides of the rotation axis.
Where two substrate holders are provided in each of the inversion units, the following operation sequence is repeatedly performed to individually transport substrates from the carrier retaining unit to the substrate processing units while a substrate inverting operation is performed by one of the inversion units. More specifically, the indexer robot unloads a substrate from one of the carriers, and loads the substrate into an upper one of the substrate holders of the one inversion unit. Thereafter, the one inversion unit rotates the two substrate holders 180 degrees about the rotation axis. Thus, the upper substrate holder which retains the loaded substrate is moved down below the rotation axis, and the (empty) lower substrate holder which retains no substrate is moved up above the rotation axis. The main transport robot unloads the substrate inverted by the one inversion unit from the lower substrate holder of the one inversion unit.
Similarly, where two substrate holders are provided in each of the inversion units, the following operation sequence is repeatedly performed to individually transport substrates from the substrate processing units to the carrier retaining unit while the substrate inverting operation is performed by the other inversion unit. More specifically, the main transport robot unloads a substrate from one of the substrate processing units, and loads the substrate into an upper one of the substrate holders of the other inversion unit. Thereafter, the other inversion unit rotates the two substrate holders 180 degrees about the rotation axis. Thus, the upper substrate holder which retains the loaded substrate is moved down below the rotation axis, and the (empty) lower substrate holder which retains no substrate is moved up above the rotation axis. The indexer robot unloads the substrate inverted by the other inversion unit from the lower substrate holder of the other inversion unit.